A housing type pipe coupling as shown in FIG. 6 is used widely in industries for creating a nonleaking union between ends of adjacent pipes butting each other.
This known housing type pipe coupling comprises a pair of circular coupling segments 1 and 2 each having a shape substantially resembling a circular arc and each provided with a circular space 6 for receiving end parts of pipes 4 and 5 provided, respectively, with circumferential grooves 3, and fastening walls 8 and 9 formed on the opposite sides of the circular space 6 and capable of being fitted in the circumferential grooves 3 of the pipes 4 and 5, a sealing elastic ring 7 to be disposed in the circular spaces 6 to create a nonleaking union between the ends of the pipes 4 and 5, and fastening means 10 for fastening together the two circular coupling segments 1 and 2.
This housing type pipe coupling compresses the elastic sealing ring 7 placed in the circular spaces 6 of the circular coupling segments 1 and 2 on the outer circumferences of the end parts of the two pipes 4 and 5 to create a nonleaking union between the ends of the pipes 4 and 5, and fixes the circular coupling segments 1 and 2 to the pipes 4 and 5 by pressing the circular fastening walls 8 and 9 against a bottom of the circumferential grooves 3 formed in the end parts of the two pipes 4 and 5.
In this housing type pipe coupling, the circular fastening walls of the circular coupling segments must be formed in dimensions such that the inner circumferences of the circular fastening walls can be pressed against the bottoms of the circumferential grooves formed in the end parts of the pipes. However, pipes of the same nominal diameter have different diameters, and the circumferential grooves are often formed in different depths, so that the pressure exerted by the circular fastening walls on the bottom surfaces of the circumferential grooves is often not constant. Consequently, it is possible that the circular fastening walls are not fastened firmly to the pipes, the end parts of the two pipes cannot be firmly joined together, the end parts of the two pipes extend, contract or bend, or the elastic sealing ring is distorted in the circular spaces.